The present invention relates to the field of radioisotope cameras. It finds particular application as a carrying case for transporting a flood source, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to the transport of other radiation sources.
Gamma-ray or scintillation cameras, also known as xe2x80x9cAnger camerasxe2x80x9d are widely used in medicinal applications to monitor the progress or distribution of a gamma-ray emitting nuclide introduced into a patient. The camera is located adjacent the part or organ of the patient concerned, for instance the brain or liver, and the distribution of the nuclide therein is indicated by the activity at various positions within the organ recorded by the camera.
The gamma camera comprises a gamma-ray sensitive crystal or scintillation crystal, such as a NaI crystal, which absorbs incident gamma rays from the patient under study and interacts with the gamma ray to produce light events. The camera gives a plurality of responses representing particular positions, and related to the position distribution and intensity of the gamma-ray emitting nuclide in the patient. An array of photomultiplier tubes is placed adjacent to the crystal in order to detect and amplify these light events so as calculate the spatial location and energy level of the incident gamma ray to produce a two dimensional image of the object which then may be displayed on a CRT or printed as a hard copy. A multielement collimator in front of the camera is used to view the patient and direct radiation to corresponding parts of the camera during testing. An example of an early radiation camera is shown in U.S. Pat. No. 3,011,057 to Anger and U.S. Pat. No. 3,911,278 to Stout, the disclosures of which are incorporated by reference.
In order to maintain the accuracy of the gamma camera, it is important to calibrate the camera regularly, so that the non-uniformity in the spatial response of the camera can be allowed for in drawing conclusions from the results of diagnostic tests. Cameras can vary in sensitivity by as much as xc2x115% over their areas, and are usually calibrated daily.
The calibration process includes exposing the gamma camera to a uniform activity in the form of a uniform flood source. This may conveniently comprise a disc, vial, or sheet containing a uniformly dispersed gamma-emitting nuclide, such as Co-57, located in particular spaced relation to the camera to provide a uniform field, whereupon camera readings indicate the sensitivity of the various parts of the camera.
The photomultiplier tubes view the scintillations and generate a resultant image. If the camera is in proper adjustment, the resultant uniform flood image is a uniform image of constant color and intensity. Variations in the color or intensity are indicative of various adjustment and calibration errors in the camera. Errors in the relative gain of the photomultiplier tubes manifest themselves in bright spots under tubes whose gain is higher than the other tubes and dark spots under tubes whose gain is lower than the other tubes.
The most commonly used Co-57 sources have from 1 to 20 mCi of activity. Due to the level of radiation, these sources come in a shielded storage case. Generally, the storage cases are relatively cumbersome and have wheels so that they may be moved from the storage area to the imaging room where the gamma camera is. The cases generally weigh between about 30-40 Kg. Because the cases are difficult to manipulate, nuclear medicine technologists frequently resort to carrying the flood source from the imaging area in their bare hands. This results in a significant radiation exposure, not just to the hands, but also to the vital organs, as the flood source is generally held at chest height.
The present invention provides a new and improved shielded carrying bag and method of use and formation which overcome the above-referenced problems and others.
In accordance with one aspect of the present invention, a carrying bag for transporting a radioactive source is provided. The bag includes at least one flexible panel comprising an outer layer and a lining formed from a radiation shielding material. The at least one panel is joined together adjacent edges thereof to define an interior space with an upper open end for receiving the radioactive source therein. The bag further includes at least one carrying handle.
In accordance with another aspect of the present invention, a method of transporting a radioactive source is provided. The method includes placing the radioactive source in a bag as described above and transporting the bag by grasping the handle with the hand.
In accordance with another aspect of the present invention, a carrying bag for transporting a flood source is provided. The bag includes a front panel member and a rear panel member. The front and rear panel members are joined along base and side edges to define an interior space with an upper open end for receiving the radioactive source therein. The front and rear panel members each include an outer layer, an inner layer, and a lining formed from a radiation shielding material between the inner and outer layers. An upper panel member shaped to cover the upper open end when the flood source is positioned within the interior space. The upper panel is connected with the rear panel member. A closure member is provided for selectively fastening the upper panel to the front panel to close the opening.
In accordance with another aspect of the present invention, a method of forming a bag for shielding a flood source is provided. The method includes covering a sheet of a radiation shielding material with a sheet of fabric to form a radiation shielding panel and folding the radiation shielding panel to define a front panel member, a rear panel member and a top panel member. The method further includes attaching the front panel member to the rear panel member along side edges thereof and forming a closure member, a first portion of the closure member being associated with the top panel member and a second portion of the closure member being associated with the front panel member. The closure member is configured for selectively engaging the top panel member and front panel member.
One advantage of at least one embodiment of the present invention is the provision of a bag which is easy to carry, and thus more likely to be used by a nuclear medicine technologist than conventional, wheeled carrying cases.
Another advantage of at least one embodiment of the present invention is that the bag is provided with carrying handles which space the radiation source from the technician and also allow the bag to be transported at the technicians side, away from the vital organs in the technician""s chest. This reduces the radiation exposure of these organs.
Yet another advantage of at least one embodiment of the present invention is that the bag is lightweight.
A still further advantage of the present invention is that the bag can be used as a shipping case, for transporting a flood source from a manufacturer to a supplier or to the facility where it is to be used, as well as a carrying case for transport between a storage area in the facility and a camera.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.